The crater

Rano Kau has a crater lake which is one
of the island's only three natural bodies of fresh water. Most of
the volcano is on the coast and has been eroded back to form high
sea cliffs which at one point have started to bite into the crater
wall. On
its northern side, the volcano slopes down to Mataveri
International Airport.

Rano Kau is in the world heritage
site of Rapa Nui National
Park and gives its name to one of the seven sections of the
park. The
principal archaeological site on Rano Kau is the ruined ceremonial
village of Orongo which is
located at the point where the sea cliff and inner crater wall
converge. One ahu with
several moai was recorded on the cliffs at Rano
Kau in the 1880s, but had fallen to the beach by the time of the
Routledge expedition in
1914.

As well as basalt, it contains several other
igneous rocks including obsidian (for which
it was one of the major sources for the island's stoneworkers) and
pumice.

The crater is almost a mile across and has its own micro climate.
Sheltered from the winds that dry most of the rest of the island,
figs and vines flourish at Rano Kau.

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Geothermal activity

At some point in the early twentieth century, the island's manager
took a photograph of steam coming out of the crater wall.